This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Confocal microscopy is a well established, powerful technique for biomedical imaging mainly because of its ability to provide optical sectioning in relatively thick specimens. Confocal diffraction phase microscopy is a new quantitative phase microscopy technique that provides quantitative phase measurements from localized sites on a sample with high sensitivity. The technique combines common-path interferometry with confocal microscopy in a transmission geometry and can be used for measuring both the optical path-length and refractive index of a transparent sample and quantifying the nanometer scale fluctuations.